## 7A.15a

$aR \to bP, Rate = -\frac{1}{a} \frac{d[R]}{dt} = \frac{1}{b}\frac{d[P]}{dt}$

KDang_1D
Posts: 127
Joined: Fri Aug 30, 2019 12:15 am
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### 7A.15a

For homework problem 7A.15, how do you know which experiments to use to calculate the order? For example for A, if you used experiments 1 and 3 instead of experiments 2 and 4, you would get a=3 instead of a=1.

nehashetty_2G
Posts: 102
Joined: Thu Jul 25, 2019 12:15 am

### Re: 7A.15a

For A, you have to ensure that only the concentrations for A are changing. Therefore, the concentrations for B must be the same (The concentration of C doesn't matter in this question specifically, so only worry about B). Based on this logic, you can use a combination of experiments such as Rate 2 and 4, but not 1 and 3 since [B] is not kept constant.

Uisa_Manumaleuna_3E
Posts: 60
Joined: Wed Sep 21, 2016 2:56 pm

### Re: 7A.15a

the above comment is absolutely correct. Always remember that the rates are gonna be different depending on the changing concentrations, so if you look at two concentrations changing at once, you can't really calculate the impact the concentration has on the overall rate change. So if you want to see the impact or order of just one concentration, you need to the two instances in which that concentration is the only thing changing with the rate of reaction.

kennedyp
Posts: 56
Joined: Tue Nov 13, 2018 12:18 am

### Re: 7A.15a

I think you have to compare two experiments where everything is constant except for one thing. For example, say for two experiments you have the same concentration of reactant A and B, but reactant C has a different concentration. You would focus on comparing those two experiments.

Bryce Ramirez 1J
Posts: 120
Joined: Sat Aug 24, 2019 12:16 am

### Re: 7A.15a

It is easiest to find two experiments where changes in one of the reactants is equal to an even factor, like 2 or 3. Then you can cross that off from the two combinations of tests required, leaving you with fewer possibilities to choose from for the next tests.